Heating pad



May 6, 1941. au. Frrz MAURICE 2,240,625

HEATING PAD Filed Nov. 29, 1939 Patented May 6, l1941 lUNITED STATES PAT-EN T OFFICE l HEATING PAD melma J. Fitz Maurice; orange, N. .r. Application November 29, 1939, Serial No. 300,761 (ci. 21a-4s) 3 Claims.

This invention is directed toan improvement in heating pads wherein the pad proper is madev up of woven material, with the heating wires intertwisted with certain of the woor threads.` and wherein means are provided to manually control the maximum quantityof heat in the pad. to

the heat.

A further object of the invention is the pro-- vision of control means located between the source of current and the pad by which the initial heat generated by the wires in the pad is manualness such that the provision of the thermostat within the pad proper presents no material projection beyond the normal surface of the pad to linterfere with the comfort of the user.-

'I'he invention is illustrated in the accompanying drawing, in which:

pad during the weaving thereof an adjustable thermostat and a iixed resistance, and in order that these elements, which of course, must have an appreciable diameter to accommodate the working parts, do not project uncomfortably from the surface oi the pad, it will be noted that the asbestos strands or threads are of very considerable diameter as compared with that of the con' ductor and intertwisted. thread and that the ,di-

ameter of these` asbestos threads approximates somewhat the diameter of the adjustable electrical thermostat and the'resistor. Under these circumstances, the pad, which is made up of a single layer, will permit the-thermostat and resistor to be embedded between the asbestos threads and present, when so embedded, relatively slight projection beyond the opposite surfaces of the pad proper and thus avoid any uncomfortable eiIect upon the user incident to the presence of these elements.

The heating conductor, as will later appear, is interwoven in the pad by being intertwisted with a Woof thread. It is, of course, to be'understood that certain only oi the Woof threads carry Figure 1 is a'general view of the wiring dia- I gram oi the pad and connections.

Figure 2 is a broken out view of the pad showing particularly the `asbestos strands and the placement of the respective thermostats in such strands.

Figure 3 is a broken longitudinal section onan enlarged scale showing the relation of the wires and the asbestos strands in` making up the pad.

Figure 4 is a side view of the manually operable current control.

Figure 5 is a plan of the same.

Figure 6 is a diagrammatic view ot the current `control circuit.

I Figure 'I is a view in elevation with the casing in outline oi.' the electrically adjustable thermostat.

'I'he pad I is made up of more or less conventional warp threads 2 and asbestos woof threads 3. Each woof thread includes a pair oi.' asbestos threads between which is arranged theheating conductor l oi the pad which, in its application as apart of the woot thread, is intertwisted with ordinary cotton or linen thread and disposed between the asbestos threads making up a singl woot strand.

As will later appear, there is embedded in the the conducting wires and that by this means the conducting or heating wire is held in xed relation in the pad and the various convolutions or lengths of this conducting wire are, by the means described, held in such spaced relation one with the other that the possibility of short-circuiting or other interruption through contact of the conducting wire sections is impossible.

The heating conductors include service wires 5 and 6 leading from aA conventional connector' I adapted to be inserted in a conventional socket. 'Ihese conductors lead through what may be termed a comfort control rheostat which includes a casing 8 and a rotatable member 9 cooperating with a portion of the circuit and designed for manual operation. The circuit within the comfort control rheostat includes a conductor I0 connected to the main conductor 0 and includinga xed carbon resistor ii of approximately 10,000 ohms in series with a carbon resistor I2 having a limit of 50,000 ohms' and acting as a variable resistor through a contact I3 controlled by themanually operable element 9. It will, of course, be appreciated that'the exact values here suggested are not necessarily controlling, and that it is to be understood that, y

adapted to be controlled by the manually operable element l. This switch Il may be closed as the manually operable element I is turned beyond the maximum resistant end of the resistance l2. Obviously, the switch I 4 is closed and the resistance I2 regulated through the operation of the manually operable element i of the casing to move the arm Il for variable control of the temperature in the pad, as will be later described.

Under this arrangement, three specific leads extendbeyond the comfort control rheostat and .are indicated more particularly as Il, IB and l1.

Of course, the rotating member 9 may indianother. In this thermostat, which is indicated generallyat A, lis provided a casing il having a block I8 at one end whichsupports bi-metallic thermostatic arms 20 extending within a coil 2| carried on an insulating tube 22. The conductors I5, Il and l1 lead into the casing to such'extending lengthwise thermostatic arms to energize contacts 23 on said arms. The ends of the casing- Il are closed by caps 24 which are rounded to prevent .ansularprojection above the surface of the pad. The arms 20 are adjusted through a conical wedge 2l and an adjusting screw 2i.A

The conductors I5, Il and I1 are led into the pad, preferably at one corner thereof, and embedded within the pad in the manner described. The heating conductor I1 is carried beyond the thermostatA and embedded in the pad according to the description in connection with Figure 3. At an appropriate point in the length of this conductor It, there is provided, embedded in the pad, a fixed thermostat, indicated at B in Figure l. This is a conventional protective thermostat in order to provide an absolute limit in temperature during the heating of the pad.

Both thermostats A and B, being arranged as in eifecta part of a heating conductor, are designed with that heating conductor or conductors to be embedded between the surface sections of the pad and to be woven into a section as a part of theparticular woof thread in that section of the pad where they are located. As the thermostat A is an adjustable thermostat, its adjustment obviously controls the passage of the current to the pad, cutting out at the maximum heat condition for which it is set and restoring` connections when the temperature condition of the pad falls below the selected cut-out degree.

It is to be understood that the pad, and particularly the Woof material thereof, is made up of good heat conducting material capable of withstanding temperatures of approximately 400 Fahrenheit without strength impairment; that the heating element proper within the pad y is in a continuous series circuit: andjthat :all

connections are made during theweaving process and embedded in the woof material.

It is, of course, to be understood .that the pad is of a single thickness and that the thermostats A and B, when embedded in the asbestos strands, present but slight projection beyond the respective surfaces of the completed pad. As the caslngs of theserespective thermostats are of circular elongated form, it is apparent that whatever projection beyond the normal surface of the pad may result from the use of the rheostats. it follows as a matter of course that no uncomfortable or really noticeable projection is present by the arrangement described which will in any manner tend to an inconvenience to the user.

What is claimed to be new is:

1. A heating pad having a pad proper of woven material, the Woof threads being substantially of asbestos, an adjustable thermostat woven into the pad between the asbestos threads, a iixed thermostat woven into the pad between the asbestos threads. the heating conductor in series with the thermostats being embedded in the pad between the asbestos woof threads, the thickness of the woof threads approaching the diameter oi the thermostats in order toavoid undue projection of the thermostats beyond the respective surfaces of the pad.

2. A heating pad having a manually operable current control between the pad and the source of current, the service conductors including re- `gistance elements whereby the temperature producing eiiect of the manual current control is governed through the adjustment of a heating conductor with respect to the resistance elements, an electrical adjustable thermostat woven into the pad and set for a predetermined` temperature control to which thermostat all wires leading from the manual current control are connected, the heating conductor being directed in series from the electrical adjustable thermostat and embedded between the threads of the pad in the weaving thereof, said heating conductor leading through a fixed thermostat within the pad to act as a maximum temperature control, the diameter of the embedded thermostats and the thickness of the threads of the pad having such relation as to prevent uncomfortable projection of the thermostats beyond the surface of the pad. V

3. A heating pad having a manually operable current control between the pad and the source of current, the service conductors including resistance elements whereby the temperature producing effect of the manual current control is governed through the adjustment of a heatingV conductor with respect to the resistance elements, an electrical adjustable thermostat woven into the pad and set for a predetermined temperature control to which thermostat all wires leading from the manual current control are connected, the heating conductor being directed RICHARD J. Frrz MAURICE. 

